This story is developing, and will be updated as more information, photos and footage comes in.

UPDATE: A statement from the UC Davis College Republicans:

“We were told by the chief of Davis police that they could not guarantee the safety of the students, the speaker, or the police officers if the event should go ahead,” said Gabrielle McDowell, vice chair of the UC Davis College Republicans.

“As the organisation hosting the event, we would have been held personally responsible for any harm caused as a result of its taking place. We were therefore forced to cancel the event” she continued.

DCR communications director Kurtie Kellner also alleges that they were told by UC Davis official Milton Lang that protesters were wielding hammers, a concern that was a significant factor in the decision to cancel.